Kairomonal responses of Tomicus destruens (Col., Scolytidae) to host volatiles α-pinene and ethanol

The Mediterranean pine shoot beetle Tomicus destruens is one of the most damaging bark beetles attacking Mediterranean pine forests in southern Europe and north Africa. We studied the attractiveness of the host volatiles alpha-pinene and ethanol at a range of release rates, alone or in combination, to T. destruens, in order to develop an attractive lure for the management of this beetle. T. destruens was attracted slightly to the host volatile alpha-pinene, but a strong synergistic effect was found in the attraction towards monoterpene when ethanol was added to the bait. The highest catches of T. destruens were obtained by the optimal blend releasing 300 mg/day of alpha-pinene and 900 mg/day of ethanol. In contrast to data reported for the related species T. piniperda, Mediterranean pine shoot beetles were clearly attracted to baits releasing ethanol alone (1350 mg/day). trans-Verbenol, which was also added to host volatiles in some tests, did not affect the response. The use of the attractive blend proposed would have a low impact on the natural enemy population of Thanasimus formicarius because of asynchronies in flight periods. Other non-target insects, such as the facultative predator or competitor Oxipleurus nodieri, were also significantly attracted. These results allow the development of an operative lure for the effective monitoring of T. destruens, although improvements by the addition of other host volatiles should be studied.